The present application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-202506, filed Jul. 3, 2001. The entire contents of the application are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a camera having a forwardly and backwardly movable lens barrel of a photographic lens and a lens-protecting barrier (lens barrier) which can be opened and closed in front of the photographic lens.
2. Description of the Related Art
With the advancement of compact designs, recent cameras with barriers tend to be designed so that the distal ends of the lens barrels and the front faces of the camera bodies, located on the same planes when the lens barrels are retracted.
For example, Japanese Published Patent Application H01-131539 discloses a camera that has a lens barrier and a lens barrel being retractable in the camera main body.
This camera is equipped with a barrier (lens barrier) for the protection of the front part of a photographic lens. The barrier can be opened and closed in front of the lens. FIG. 20 is a cross-sectional view showing the surroundings of the lens barrel of the camera when the barrier is locked to the camera.
In FIG. 20, reference numeral 101 represents the lens barrel, reference numeral 104 represents the barrier, reference numeral 104a represents a fitting portion (lock pin cutout) formed in the barrier, reference numeral 110 represents a lock pin and reference numeral 111 represents a leaf spring. As shown in FIG. 20, when the lens barrel 101 is extracted (protruding) from the camera main body, the lock pin 110 locks the barrier 104 at an open position so as to prevent the barrier 104 from being moved in a closing direction and contacting the lens barrel 101. Consequently, when the lens barrel 101 is located at the extended position, the barrier 104 does not interfere with the lens barrel 101 even when the barrier 104 is pressed in the P direction, and thus the forward or backward movement of the lens barrel 101 is not disturbed.
In the disclosed camera, when the barrier is in the closed position, the periphery of the lower portion of the retracted lens barrel 101 presses the L-shaped portion of the lock pin 110 against the urging force (tension) of the leaf spring 111 to move the lock pin 110 down. When the barrier 104 is opened, the lens barrel 101 starts to extract from the retracted state. At a specific point of this extraction, the pressing force on the lock pin 110 by the lower flange of the lens barrel 101 is released, and the lock pin 110 is pushed out to the front side of the camera by the urging force of the leaf spring 111 and engages with the fitting portion (lock pin cutout) 104a to lock the barrier 104. As a result of the described process, there is some time lag between the time at which the barrier 104 reaches to the open position and the time at which it is locked. Therefore, if an operator presses the barrier 104 in the closing direction P just after he or she opens it, the barrier 104 might move in the closing direction P and hit the lens barrel, 101 or the lens barrel 101 might touch the back surface of the barrier 104. Therefore, the mechanism described above for extracting the lens barrel 101 can cause damage by the contact between the barrier 104 and the lens barrel 101.
The present invention provides an improved mechanism for extracting and retracting lens barrels, and/or for locking and unlocking a lens barrier to avoid contact between the lens barrel and lens barrier caused by an error.
The present invention relates to a camera equipped with a forwardly and backwardly movable photographic lens and a lens protecting barrier (lens barrier) which can be opened and closed in front of the photographic lens. The present invention has some technical features to reduce the risk of contact between the barrier and the photographic lens caused by careless operation of the camera. All the technical features may be used to implement the present invention; however, each one of the technical features has a unique merit for implementation. Consequently, it is not required to implement all the technical features of the present invention. A user of the present invention may use some or all of the technical features which are necessary in accordance with his or her situation.
In various embodiments of the present invention, the camera of the present invention may be a film camera, a digital camera, a video camera or any electronic equipment (for example, a cellular phone, a computer, PDA) having a camera installed therein.
In the present invention, a photographic lens includes a photographic lens and a lens barrel holding the photographic lens unless the photographic lens and the lens barrel are distinguishably described.
The present invention is designed to be used with a camera having a photographic lens which can be forwardly and backwardly moved along the optical axis direction of the lens system and a barrier which can cover the front face or a portion of the front face of the photographic lens when the lens is retracted. The barrier is movable between a closed position at which it covers the front face of the photographic lens or a portion of the front face and a retreated position at which it does not cover the front face of the photographic lens. The path of the photographic lens and the path of the barrier cross each other; therefore the barrier must locate at the retreated position when the photographic lens moves forward or backward and may locate at the closed position only when the photographic lens is retracted in the camera main body.
The first technical feature of the invention resides in that when the barrier is opened, the barrier is locked by using the movement of the barrier itself to the retreated position (the barrier is to be locked at least so as not to be moved in the closing direction). Specifically, the lock operation of the barrier is caused directly by the movement of the barrier to the retreated position, whereby the barrier can be quickly locked when it is moved to the retreated position. As an example to implement this lock operation, the lock member for locking the barrier may be kept under tension in the locking direction so that it can automatically and immediately lock the barrier by the urging force when the barrier comes to the retracted position, and thereby the locking operation becomes possible.
The second technical feature of the invention resides in that, in the first technical feature, the forward movement of the photographic lens is started only after the barrier lock by the lock member is accomplished. By this technical feature, even when the barrier is pressed in the closing direction during the forward movement of the photographic lens, the barrier cannot be moved in the closing direction because it has already been locked. Consequently, the contact between the barrier and the photographic lens can be effectively prevented. As an example to achieve this feature, a switch is provided to detect that the barrier has reached the position where it is to be locked, and the detection makes a motor start to drive the photographic lens in advancing direction.
The third technical feature of the invention resides in that, in a phase of retracting the photographic lens into the camera main body and subsequently closing the lens barrier, the lock of the barrier is released by using the retracting motion of the photographic lens. With this feature, the timing for releasing the barrier""s lock can be preferably chosen in connection with the retracting photographic lens""s current position. The releasing timing can be chosen with reference to the photographic lens""s position, thereby it is possible to defer the release of the barrier""s lock until after the photographic lens has sufficiently retracted. Thus there is no possibility of contact between the barrier and the photographic lens with respect to each other, even if the barrier is pushed in the closing direction. As an example to achieve this feature, a member for releasing the barrier lock (lock-release engaging portion) is provided on the photographic lens. This member engages with the lock member during the retraction of the photographic lens, and pushes the lock member by using the retraction movement to unlock it.
The fourth technical feature of the invention resides in that, in the third technical feature, a mechanism for avoiding the engagement between the lock-release engaging portion and the lock member during the advancement of the photographic lens is adopted. The lock-release engaging portion which engages with the lock member during retraction of the photographic lens may also engage with the lock member during advancement of the photographic lens, because the photographic lens usually advances and retracts along the same path. The lock-release engaging portion is intended to operate only in the retracting movement of the photographic lens, thus the engagement in the advancing movement of the photographic lens may cause some unexpected problems. This mechanism is provided to avoid the problems. As an example to achieve this feature, a slant surfaces are provided on the surfaces, onto which the lock-release engaging portion and the lock member contact each other during the advancing movement of the photographic lens, so that the lock-release engaging portion and the lock member slide on each other along the slant surfaces during the advancing movement of photographic lens. This sliding movement applies the force in a direction different than the advancing direction of the photographic lens to the lock member, thereby the force moves the lock member out of the engaging position.
The fifth technical features of the invention resides in that the engagement of the lock-release engaging portion and the lock member is released by using the closing operation of the barrier. When the release of the lens barrier is to be made, the lock-release engaging portion engages the lock member during the retracting movement of the photographic lens. The lock-release engaging portion pushes the lock member to unlock the lens barrier by using the retracting movement of the photographic lens. But after the releasing of the lock, the lock-release engaging portion may still be engaged and push the lock member, thus the lock member can not lock the barrier again until the engagement with the lock-release engaging portion is released. Therefore, it is required to release the engagement between the lock-release engaging potion and the lock member after the unlocking of the lens barrier is accomplished. In this feature of the invention, the engagement is released by using the closing operation of the barrier. As an example to achieve this feature, it is desirable to provide a lock engaging portion on the lens barrier for engaging with the lock member during the lens barrier""s closing operation. This lock engaging portion engages with the lock member, pushes it by the closing movement of the barrier, whereby the engagement between the lock member and the lock-release engaging portion is released.
The sixth technical feature of the invention resides in that, two specific positions are specified as positions of the retreated lens barrier with respect to the photographic lens"" path (two positions are appointed from along the lens barrier""s path in which the lens barrier is retreated from the photographic lens""s path). One is a semi-open position at which the lens barrier is to be locked (to prevent motion in closing direction), and the other is an open position at which the barrier is more widely opened and is detected by a switch. The switch is used to control the driving motor of the photographic lens. When the barrier comes into the open position, it is detected with the switch, and then the photographic lens starts the forward motion from the retracted position. On the other hand, when the barrier is detached from the switch, the retracting motion of the photographic lens is started. Therefore, the driving of the photographic lens is carried out in connection with the opening and closing operation of the barrier, and it is not required to provide a button for driving the photographic lens. This is particularly effective in a case where the barrier is manually moved. With the implementation of the technical feature, there is some extra time period between the completion of the lock and the start of the forward movement of the photographic lens (this time period corresponds with the time period in which the barrier moves from the semi-open position to the open position), so that the possibility of malfunction can be reduced. Further, when the barrier is being closed, the closing operation of the barrier is temporarily stopped at the semi-open position, and the automatic retraction of the photographic lens is started. Therefore, when (by adopting the third technical feature, for example) the lock of the barrier may be released after the photographic lens is retracted to a position at which the closing operation of the barrier is not disturbed, and thus the operation can be smoothly performed while the possibility of the contact between the photographic lens and the barrier is reduced.
The switch is preferably set to detect the departure of the barrier when the barrier just reaches the semi-open position from the open position, so an operator may not notice a difference between the two positions, (the barrier locking position (the semi-open position) and the motor-controlling position (the open position)), and may enjoy a smooth operational feeling.
The switch of the second or sixth technical feature may include mechanical types, electrical types, optical types, magnetic types or any other type of sensing device or method. In one embodiment of the invention, the switch may be, for example, a photoelectric switch.
In many cameras, the photographic lenses are, at least partially, sunken into the camera main bodies when they are retracted. When in this condition, the cameras are usually disabled from taking photographs. When the photographic lenses are extended from the bodies, the cameras become to be able to take photographs. However, the present invention does not require a connection between the location of the photographic lens and the operational conditions of the camera.